doc: boards: amlogic: add documentation for GS-King-X

GS-King-X is also supported with the beelink-s922x FIP sources and can use
the GT-King defconfig. Add a board document with instructions.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Link: https://lore.kernel.org/r/20230320114609.930145-33-christianshewitt@gmail.com
[narmstrong: fixed doc build]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
diff --git a/board/amlogic/beelink-s922x/MAINTAINERS b/board/amlogic/beelink-s922x/MAINTAINERS
index 47b6227..8dddeb9 100644
--- a/board/amlogic/beelink-s922x/MAINTAINERS
+++ b/board/amlogic/beelink-s922x/MAINTAINERS
@@ -3,8 +3,9 @@
 S:	Maintained
 L:	u-boot-amlogic@groups.io
 F:	board/amlogic/beelink-s922x/
+F:	configs/beelink-gsking-x_defconfig
 F:	configs/beelink-gtking_defconfig
 F:	configs/beelink-gtkingpro_defconfig
-F:	configs/beelink-gsking-x_defconfig
+F:	doc/board/amlogic/beelink-gskingx.rst
 F:	doc/board/amlogic/beelink-gtking.rst
 F:	doc/board/amlogic/beelink-gtkingpro.rst
diff --git a/doc/board/amlogic/beelink-gskingx.rst b/doc/board/amlogic/beelink-gskingx.rst
new file mode 100644
index 0000000..8a8296e
--- /dev/null
+++ b/doc/board/amlogic/beelink-gskingx.rst
@@ -0,0 +1,122 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+U-Boot for Beelink GS-King-X (S922X)
+====================================
+
+The Shenzen AZW (Beelink) GS-King-X is based on the Amlogic W400 reference board with an
+S922X-H chip and the following specifications:
+
+- 4GB LPDDR4 RAM
+- 64GB eMMC storage
+- 10/100/1000 Base-T Ethernet
+- AP6356S Wireless (802.11 a/b/g/n/ac, BT 4.1)
+- HDMI 2.1 video
+- S/PDIF optical output
+- 2x ESS9018 audio DACs
+- 4x Ricor RT6862 audio amps
+- Analogue headphone output
+- 1x USB 2.0 OTG port
+- 3x USB 3.0 ports
+- IR receiver
+- 1x micro SD card slot (internal)
+- USB SATA controller with 2x 3.5" drive bays
+- 1x Power on/off button
+
+Beelink do not provide public schematics, but have been willing to share them with known
+distro developers to assist with development.
+
+U-Boot Compilation
+------------------
+
+.. code-block:: bash
+
+    $ export CROSS_COMPILE=aarch64-none-elf-
+    $ make beelink-gsking-x_defconfig
+    $ make
+
+U-Boot Signing with Pre-Built FIP repo
+--------------------------------------
+
+.. code-block:: bash
+
+    $ git clone https://github.com/LibreELEC/amlogic-boot-fip --depth=1
+    $ cd amlogic-boot-fip
+    $ mkdir my-output-dir
+    $ ./build-fip.sh beelink-s922x /path/to/u-boot/u-boot.bin my-output-dir
+
+U-Boot Manual Signing
+---------------------
+
+Beelink released an Amlogic "SDK" dump in their forums but the U-Boot sources included
+result in 2GB RAM detected. The following FIPs were generated with newer sources and
+detect 4GB RAM: https://github.com/LibreELEC/amlogic-boot-fip/tree/master/beelink-s922x
+
+.. code-block:: bash
+
+    $ wget https://github.com/LibreELEC/amlogic-boot-fip/archive/master.zip
+    $ unzip master.zip
+    $ export FIPDIR=$PWD/amlogic-boot-fip/beelink-s922x
+
+Go back to the mainline U-Boot source tree then:
+
+.. code-block:: bash
+
+    $ mkdir fip
+    $ cp $FIPDIR/* fip/
+    $ cp u-boot.bin fip/bl33.bin
+
+    $ sh fip/blx_fix.sh \
+         fip/bl30.bin \
+         fip/zero_tmp \
+         fip/bl30_zero.bin \
+         fip/bl301.bin \
+         fip/bl301_zero.bin \
+         fip/bl30_new.bin \
+         bl30
+
+    $ sh fip/blx_fix.sh \
+         fip/bl2.bin \
+         fip/zero_tmp \
+         fip/bl2_zero.bin \
+         fip/acs.bin \
+         fip/bl21_zero.bin \
+         fip/bl2_new.bin \
+         bl2
+
+    $ fip/aml_encrypt_g12b --bl30sig --input fip/bl30_new.bin \
+                           --output fip/bl30_new.bin.g12a.enc \
+                           --level v3
+    $ fip/aml_encrypt_g12b --bl3sig --input fip/bl30_new.bin.g12a.enc \
+                           --output fip/bl30_new.bin.enc \
+                           --level v3 --type bl30
+    $ fip/aml_encrypt_g12b --bl3sig --input fip/bl31.img \
+                           --output fip/bl31.img.enc \
+                           --level v3 --type bl31
+    $ fip/aml_encrypt_g12b --bl3sig --input fip/bl33.bin --compress lz4 \
+                           --output fip/bl33.bin.enc \
+                           --level v3 --type bl33
+    $ fip/aml_encrypt_g12b --bl2sig --input fip/bl2_new.bin \
+                           --output fip/bl2.n.bin.sig
+    $ fip/aml_encrypt_g12b --bootmk \
+                           --output fip/u-boot.bin \
+                           --bl2 fip/bl2.n.bin.sig \
+                           --bl30 fip/bl30_new.bin.enc \
+                           --bl31 fip/bl31.img.enc \
+                           --bl33 fip/bl33.bin.enc \
+                           --ddrfw1 fip/ddr4_1d.fw \
+                           --ddrfw2 fip/ddr4_2d.fw \
+                           --ddrfw3 fip/ddr3_1d.fw \
+                           --ddrfw4 fip/piei.fw \
+                           --ddrfw5 fip/lpddr4_1d.fw \
+                           --ddrfw6 fip/lpddr4_2d.fw \
+                           --ddrfw7 fip/diag_lpddr4.fw \
+                           --ddrfw8 fip/aml_ddr.fw \
+                           --level v3
+
+Then write U-Boot to SD or eMMC with:
+
+.. code-block:: bash
+
+    $ DEV=/dev/boot_device
+    $ dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=512 skip=1 seek=1
+    $ dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=1 count=440
diff --git a/doc/board/amlogic/index.rst b/doc/board/amlogic/index.rst
index 808c857..7c4c161 100644
--- a/doc/board/amlogic/index.rst
+++ b/doc/board/amlogic/index.rst
@@ -87,6 +87,7 @@
 
    bananapi-cm4io
    bananapi-m5
+   beelink-gskingx
    beelink-gtking
    beelink-gtkingpro
    jethub-j80